JPWO2014034395A1 - Paint for exhaust system parts and exhaust system parts - Google Patents

Abstract

An exhaust system component of the present invention is an exhaust system component comprising a base material made of metal and a single surface coating layer formed on the surface of the base material, wherein the surface coating layer comprises silica. A non-crystalline inorganic material layer, a non-crystalline inorganic material particle containing zirconia dispersed in the non-crystalline inorganic material layer, a non-crystalline inorganic material layer, and a non-crystalline inorganic material layer. The reaction product particles are crushed or acicular particles, and the ratio of the average pore size of the pores to the average particle size of the particles of the crystalline inorganic material. The average particle diameter of the crystalline inorganic material particles / the average pore diameter of the pores is 0.1 to 10, and the surface coating layer includes the amorphous inorganic material, the pore former, and the crystallinity. It is formed by applying and heating a paint for exhaust system parts containing inorganic particles on a substrate. And said that you are.

Description

The present invention relates to a paint for exhaust system parts and an exhaust system part.

In order to treat harmful substances contained in the exhaust gas discharged from the engine, a catalytic converter is provided in the path of the exhaust pipe.
In order to increase the purification efficiency of harmful substances by the catalytic converter, it is necessary to maintain the temperature of the exhaust gas and the exhaust pipe through which the exhaust gas circulates at a temperature suitable for catalyst activation (hereinafter also referred to as catalyst activation temperature).

In the conventional exhaust gas purification system, the temperature of the catalytic converter at the start of the engine is lower than the catalyst activation temperature, the catalyst does not function, and it is difficult to completely prevent emission of harmful substances at the start of the engine. .
For this reason, the exhaust pipe connected to the engine is required to be heated to the catalyst activation temperature in a short time from the start of the engine.

In order to meet such a demand, Patent Documents 1 to 3 include a base material made of metal and an inorganic material surface layer made of crystalline and amorphous inorganic material, and the heat of the inorganic material surface layer is described above. A structure has been proposed in which the conductivity is lower than the thermal conductivity of the substrate, and the infrared emissivity of the inorganic material surface layer is higher than the infrared emissivity of the substrate. Specifically, for example, manganese dioxide, copper oxide or the like is used as the crystalline inorganic material, and barium-silica glass or the like is used as the amorphous inorganic material.

JP 2008-69383 A JP 2009-133213 A JP 2009-133214 A

The surface layer proposed in Patent Documents 1 to 3 uses a low thermal conductivity oxide such as barium-silica glass on the surface of the base material. Therefore, it cannot be said that the catalyst converter has sufficient heat insulating properties to raise the temperature of the catalytic converter to the catalyst activation temperature in a short time.

In order to improve the heat insulating property of the surface coating layer, the present inventors tried to introduce pores into the surface coating layer, thereby further improving the heat insulating property. However, by simply introducing pores into the surface coating layer, the surface coating layer made of an amorphous inorganic material has a low viscosity when the substrate becomes high temperature, and coalescence of pores occurs, It became clear that it became a pore. When such pores are made into an air hole, the strength of the surface coating layer decreases, and when the temperature of the substrate suddenly increases, there arises a problem that it is easily broken by thermal stress. In addition, there is a problem that the heat conductivity increases and the heat insulation performance deteriorates due to an increase in convective heat transfer and radiation heat transfer caused by the pores.

The present invention has been made to solve such a problem, and since the pores dispersed in the surface coating layer are difficult to coalesce even at a high temperature, the surface coating layer formed on the substrate surface is Providing paints for exhaust system parts that can produce exhaust system parts that have sufficient heat insulation performance for a long time and have excellent heat retention at low temperatures, and exhaust system parts that use the paints for exhaust system parts The purpose is to do.

That is, the paint for exhaust system parts of the present invention is
A paint for exhaust system parts to be applied to a base material made of metal,
The exhaust system paint includes an amorphous inorganic material containing silica, a crystalline inorganic material particle containing zirconia, and a pore former particle.
The average particle size of the crystalline inorganic material particles is 0.1 to 150 μm,
The weight of the crystalline inorganic material particles with respect to 100 parts by weight of the amorphous inorganic material is 30 to 180 parts by weight,
The average particle diameter of the pore former particles is 0.1 to 25 μm,
The weight of the pore former particles is 0.001 to 1 part by weight with respect to 100 parts by weight of the amorphous inorganic material.

In the paint for exhaust system parts of the present invention, when the paint having the above composition is applied to a base material made of metal and baked, a crystal having an average particle diameter of 0.1 to 150 μm inside as a surface coating layer on the surface of the base material. A surface coating layer composed of a layer of an amorphous inorganic material in which pores having a predetermined pore diameter due to the particles of the porous inorganic material and the pore-forming material are dispersed is formed, and the pores are dispersed in the surface coating layer Therefore, the pores prevent heat conduction inside the solid, and excellent heat insulating properties can be obtained.
The pores formed inside the surface coating layer are small compared to the thickness of the surface coating layer and stay in the surface coating layer, so the thickness of the surface coating layer is set to an appropriate range that does not lose the heat insulating function. Is possible.

In addition, since the crystalline inorganic material particles are dispersed in the formed surface coating layer, the crystalline inorganic material particles become an obstacle to the movement of pores even when the surface coating layer becomes high temperature. The movement of the air is hindered, and it is possible to prevent the heat insulation performance from deteriorating due to the coalescence of the pores.
Furthermore, since the crystalline inorganic material contains zirconia and the amorphous inorganic material contains silica, the reaction between the amorphous inorganic material and the crystalline inorganic material reacts with the particles of the crystalline inorganic material. Crystals of reaction product particles produced by the above (for example, Ba _α Zr _β Si _γ O _σ (BaZrSi ₃ O ₉ , Ba ₂ Zr ₂ Si ₃ O ₂ ), zircon (ZrSiO ₄ )) crystals grow, Since the movement is further hindered, high heat insulation performance can be maintained.

Furthermore, the crystalline inorganic material particles are excellent in heat resistance and play a role of mechanically strengthening the surface coating layer, thus preventing the occurrence of cracks and the like due to deterioration of the mechanical strength of the surface coating layer. be able to. Further, since the reaction product particles are invaded into the amorphous inorganic material in a complicated manner, a spike effect that firmly fixes the crystalline inorganic material in the surface coating layer is obtained, and the mechanical strength of the surface coating layer is further increased.

In the exhaust system component paint of the present invention, it is desirable that carbon, carbonate, or a foaming agent is used as the pore former.
When the pore-forming material is used, when the surface coating layer is formed, the pore-forming material is decomposed and gasified, or bubbles are generated, resulting in pores inside the surface coating layer, The surface coating layer can exhibit heat insulation performance.

In the exhaust system component paint according to the present invention, the pore former is preferably changed to a gas at 600 to 1000 ° C.
When the pore-forming material changes to gas at the above temperature, the amorphous inorganic material melts on the base material to form a layer, then becomes a gas inside and forms pores inside the surface coating layer. it can.
As a method for forming the surface coating layer, a method in which a base material coated with a paint for exhaust system parts is placed in a furnace such as an oven and baked at a high temperature can be employed.
Alternatively, the exhaust system component paint may be applied to the substrate and then dried at a low temperature. When drying at low temperature, the surface coating layer is not formed at that time.For example, after applying and drying paint for exhaust system parts using the exhaust pipe as a base material, the exhaust pipe is actually attached to a vehicle or the like. When arranged, the exhaust system component paint is baked with the high-temperature exhaust gas flowing in the exhaust pipe to form a surface coating layer. In this way, the baking process can be replaced by heating with exhaust gas and baking to simplify the manufacturing process.

When the temperature of the pore-forming material is changed to less than 600 ° C., the amorphous inorganic material is melted and decomposed before the film is formed, so that the pores are not formed well, When the temperature at which the pore-forming material changes to a gas exceeds 1000 ° C., it is necessary to heat the amorphous inorganic material to a high temperature, and the viscosity of the molten amorphous inorganic material decreases. It becomes difficult to form a layer.

In the exhaust system paint according to the present invention, the crystalline inorganic material particles preferably contain 20% by weight or more of zirconia.
When the particles of the crystalline inorganic material contain 20% by weight or more of zirconia, inorganic particles having excellent mechanical properties such as strength and excellent heat resistance are included therein. For this reason, the formed surface coating layer is excellent in mechanical characteristics and heat resistance.
Zirconia is also a crystalline inorganic material with excellent corrosion resistance. Therefore, even when the surface coating layer of the exhaust system component is directly exposed to high-temperature exhaust gas, the surface coating of the exhaust system component is caused by nitrogen oxide (NOx) and / or sulfur oxide (SOx) contained in the exhaust gas. It is possible to prevent the layer from corroding.
When the content of zirconia in the particles of the crystalline inorganic material is less than 20% by weight, the number of reaction product particles decreases or no reaction product particles are generated.

In the exhaust system component paint according to the present invention, the amorphous inorganic material preferably contains 20% by weight or more of silica.
When the amorphous inorganic material contains 20% by weight or more of silica, the reaction between the crystalline inorganic material and the amorphous inorganic material proceeds more easily and the reaction product particles are more likely to be precipitated. The reaction product particles deposited from the surface of the equipment more effectively inhibit the movement of the pores. Furthermore, since the reaction product particles grown from the crystalline inorganic material have a spike effect that firmly fixes the crystalline inorganic material in the surface coating layer, the crystalline inorganic material particles are firmly attached to the amorphous inorganic material layer. Fixing further improves the mechanical properties of the surface coating layer.
When the content of silica in the amorphous inorganic material is less than 20% by weight, the reaction between the crystalline inorganic material particles and the amorphous inorganic material is unlikely to proceed.

The exhaust system parts of the present invention are:
A base material made of metal;
An exhaust system component comprising one surface coating layer formed on the surface of the substrate,
The surface coating layer includes an amorphous inorganic material layer containing silica, crystalline inorganic material particles containing zirconia dispersed inside the amorphous inorganic material layer, crystalline inorganic material particles and the above Consists of reaction product particles and pores generated by reaction with the amorphous inorganic material layer,
The reaction product particles are crushed or acicular particles,
The ratio of the average pore diameter of the pores to the average particle diameter of the particles of the crystalline inorganic material (average particle diameter of the particles of the crystalline inorganic material / average pore diameter of the pores) is 0.1 to 10,
The surface coating layer is formed by applying and heating a coating for exhaust system parts containing the amorphous inorganic material, pore-forming material particles, and the crystalline inorganic material particles on a substrate. Features.

In the exhaust system component according to the present invention, the surface coating layer includes an amorphous inorganic material layer containing silica, crystalline inorganic material particles containing zirconia dispersed inside the amorphous inorganic material layer, It consists of reaction product particles and pores generated by the reaction between the crystalline inorganic material particles and the amorphous inorganic material layer. Since the pores exist in the surface coating layer, the pores are contained inside the solid. It prevents heat conduction and provides excellent heat insulation properties.

Further, in the surface coating layer, particles of the crystalline inorganic material are dispersed, and the ratio of the average pore diameter of the pores to the average particle diameter of the particles of the crystalline inorganic material (the average of the particles of the crystalline inorganic material) Since the particle diameter / the average pore diameter of the pores) is 0.1 to 10, when the surface coating layer becomes high temperature, the particles of the crystalline inorganic material become an obstacle to the movement of the pores, and the movement of the pores Is prevented, and it is possible to prevent the heat insulation performance from deteriorating due to the coalescence of the pores.

When the ratio of the average pore diameter of the pores to the average particle diameter of the particles of the crystalline inorganic material (average particle diameter of the particles of the crystalline inorganic material / average pore diameter of the pores) is less than 0.1, Since the crystalline inorganic material does not have the function of becoming an obstacle, the coalescence and movement of pores occur, leading to a decrease in heat insulation performance.

On the other hand, when the ratio of the average pore diameter of the pores to the average particle diameter of the particles of the crystalline inorganic material (the average particle diameter of the particles of the crystalline inorganic material / the average pore diameter of the pores) exceeds 10, the crystalline inorganic material However, the pores are crushed and easily broken, and the mechanical strength and heat insulating performance of the surface coating layer are likely to be lowered.
As described above, if the particle size of the crystalline inorganic material is too small or too large with respect to the pore diameter, the crystalline inorganic substance has a small physical inhibitory effect on the movement of the pores. The ratio of the average pore diameter of the pores to the average particle diameter of the inorganic material particles (the average particle diameter of the crystalline inorganic material particles / the average pore diameter of the pores) is preferably in the range of 0.1 to 10. 5 to 5 is more preferable. The thermal insulation and the mechanical strength of the surface coating layer are basically in a trade-off relationship, and in the range of 0.5 to 5, the best balance between thermal insulation and strength is the best when used as automotive parts. ing.
In addition, the surface coating layer having a high temperature means a case where the temperature of the surface coating layer is 750 ° C. or higher.

In addition, the crystalline inorganic material particles mechanically strengthen the surface coating layer and have excellent heat resistance, so the surface coating layer has excellent heat resistance, and cracks and the like are generated due to deterioration of mechanical strength. Can be prevented.

Furthermore, since the surface coating layer contains crushed or acicular reaction product particles generated by the reaction between the crystalline inorganic material particles and the amorphous inorganic material layer, the reaction product particles Therefore, the movement of the pores is inhibited, and the surface coating layer can maintain high heat insulation performance. Here, the crushed shape is a shape in which acicular crystals are further grown and branched from acicular shapes, and refers to the shape of an aggregate of a plurality of acicular crystals.

In the exhaust system component of the present invention, it is desirable that 5 to 50% by weight of the crystalline inorganic material particles are in contact with the pores having a pore diameter of 0.1 to 50 μm.
When the pores are in contact with and adhere to the particles of the crystalline inorganic material, the pores hardly move away from the particles of the crystalline inorganic material even when the temperature is high, and the high thermal insulation of the surface coating layer is maintained. be able to.
Whether or not the particles of the crystalline inorganic material are in contact with the pores can be determined by observing the surface with a scanning electron microscope (SEM) after cutting the surface coating layer.

When the crystalline inorganic material particles in contact with the pores are less than 5% by weight, the crystalline inorganic material does not contribute to the suppression of pore movement, and coalescence of pores occurs, resulting in a decrease in heat insulation performance. On the other hand, when the amount of the crystalline inorganic material particles in contact with the pores exceeds 50% by weight, the content of the crystalline particles in the surface coating layer is too large, so that the mechanical strength or heat insulation performance of the surface coating layer is reduced. To do.

Assuming that pores having an average pore diameter of less than 0.1 μm are in contact with the particles of the crystalline inorganic material, it is technically difficult to form pores of such a size. Since it is necessary to use a special material such as a very small pore former, the material cost increases rapidly, which is not preferable.
On the other hand, when the pores having a pore diameter exceeding 50 μm are in contact with the particles of the crystalline inorganic material, the pores are often already joined by movement. As described above, when pores having a large pore diameter are formed in the surface coating layer, the solid portion of the surface coating layer is reduced and the mechanical properties of the surface coating layer are deteriorated. In addition, since such a large pore promotes a heat dissipation effect by convective heat transfer and radiative heat transfer in the pore, the heat insulation is reduced.

In the exhaust system component of the present invention, the crystalline inorganic material particles preferably contain 20% by weight or more of zirconia.
Zirconia is a crystalline inorganic material with excellent heat resistance. Therefore, even when the surface coating layer of the exhaust system component is exposed to a high temperature, since the zirconia existing in the surface coating layer of the exhaust system component is difficult to soften, the surface coating layer is peeled off from the base material made of metal. This can be prevented.
Zirconia is also a crystalline inorganic material with excellent corrosion resistance. Therefore, even when the surface coating layer of the exhaust system component is directly exposed to high-temperature exhaust gas, the surface coating of the exhaust system component is caused by nitrogen oxide (NOx) and / or sulfur oxide (SOx) contained in the exhaust gas. It is possible to prevent the layer from corroding.
When the content of zirconia in the particles of the crystalline inorganic material is less than 20% by weight, the reaction product particles with the amorphous inorganic material cannot be sufficiently grown, and the crystalline inorganic material particles including the reaction product particles The ability to prevent the movement of pores is reduced, and the mechanical strength of the surface coating layer is reduced.

In the exhaust system component of the present invention, the porosity of the surface covering material layer is preferably 30 to 80%.
When the porosity of the surface covering material layer is 30 to 80%, the amount of pores contributing to the heat insulating properties is sufficient, and the surface covering material layer can maintain good heat insulating properties.
When the porosity of the surface coating material layer is less than 30%, the heat insulating properties generated due to the presence of pores are not sufficient, whereas when the porosity of the surface coating material layer exceeds 80%, the surface coating layer Therefore, the mechanical strength is weak.

In the exhaust system part of the present invention, the average pore diameter of the pores is preferably 0.1 to 50 μm.
When the average pore diameter of the pores is 0.1 to 50 μm, the pores are easily dispersed in the surface coating layer, and the high thermal insulation of the surface coating layer can be maintained.
When the average pore diameter is less than 0.1 μm, it is technically difficult to form pores of such a size, and in order to form such pores, a very small pore former is used. Since it is necessary to use a special material, the material cost increases rapidly, which is not preferable.
On the other hand, when the average pore diameter exceeds 50 μm, the pores are often already joined by movement. As described above, when pores having a large pore diameter are formed in the surface coating layer, since the solid portion of the surface coating layer is small, the mechanical properties of the surface coating layer are deteriorated. In addition, such large pores are deteriorated in heat insulation performance because the heat dissipation effect is promoted by convective heat transfer and radiative heat transfer in the pores.

In the exhaust system component of the present invention, the average particle diameter of the crystalline inorganic material particles is preferably 0.1 to 150 μm.
When the average particle size of the crystalline inorganic material particles is 0.1 to 150 μm, the crystalline inorganic material particles are larger than the pore size, and even if the surface coating layer becomes high temperature, the crystalline inorganic material The movement of the pores is hindered by the particles, and high heat insulation can be maintained.
When the average particle size of the crystalline inorganic material particles is less than 0.1 μm, it becomes difficult to prevent the movement of pores, and further, since the zirconia content is small, it is difficult to maintain high heat resistance after drying. On the other hand, if the average particle diameter of the crystalline inorganic material particles exceeds 150 μm, the distance between the surface coating layer surface and the crystalline inorganic material particles increases, and the surface cracks even with a slight stress such as bending. Is likely to occur.

In the exhaust system component of the present invention, the average particle size of the reaction product particles is preferably 0.01 to 25 μm.
In the reaction product particles produced by the reaction between the crystalline inorganic material and the amorphous inorganic material, crystals grow from the surface of the crystalline inorganic material, so the average particle size of the reaction product particles is 0.01 to 25 μm. And, it has the same effect that the length of the crystalline inorganic material particles becomes longer, and the effect of preventing the movement of pores is great.
When the average particle size of the reaction product particles is less than 0.01 μm, the effect of preventing the movement of pores is small. Further, if the average particle diameter of the reaction product particles exceeds 25 μm, the reaction product particles present in the surface coating layer are large in size, so that it becomes necessary to make the surface coating layer thicker than necessary, thereby surface coating. Since the bending stress of the layer increases, cracks are likely to occur.

In the exhaust system component of the present invention, the thickness of the surface coating layer is preferably 50 to 2000 μm.
When the thickness of the surface coating layer is the above-described thickness, the ratio of the pore size to the thickness of the surface coating layer and the particle size of the crystalline inorganic material is in a suitable range, and the heat insulation performance and mechanical properties Can be maintained better.

When the thickness of the surface coating layer is less than 50 μm, the thickness of the surface coating layer is too thin, so that sufficient heat insulation performance cannot be exhibited when used as an exhaust system component. On the other hand, when the thickness of the surface coating layer exceeds 2000 μm, the surface coating layer is too thick, and therefore, when subjected to thermal shock, the surface of the surface coating layer bonded to the base material and the surface exposed to the atmosphere The temperature difference tends to be large, and the surface coating layer is easily broken.

In the exhaust system component of the present invention, the thermal conductivity of the surface coating layer at room temperature is desirably 0.05 to 2 W / mK.

In the exhaust system component of the present invention, when the thermal conductivity of the surface coating layer at room temperature is 0.05 to 2 W / mK, the heat insulation is excellent, and the thermal conductivity is difficult to increase even at high temperatures. It is possible to prevent the temperature of exhaust gas and the like from decreasing.
Realizing a surface coating layer having a thermal conductivity of less than 0.05 W / mK at room temperature is not easy in view of the balance between both technical and economic aspects. If the thermal conductivity of the layer at room temperature exceeds 2 W / mK, the heat retention of the exhaust pipe in the low temperature region becomes insufficient, and for example, when used in the exhaust pipe, the temperature of the catalytic converter reaches the catalyst activation temperature. It takes a long time.

In the exhaust system component of the present invention, the crystalline inorganic material particles may be zirconia or a composite oxide composed of zirconia and at least one of yttria, calcia, magnesia, ceria, alumina, and hafnia. desirable.

Since the oxide made of the above material used in the exhaust system component of the present invention has low thermal conductivity, the heat insulation of the surface coating layer is further improved by using the oxide made of the above material as particles of the crystalline inorganic material. be able to.

In the exhaust system component of the present invention, the amorphous inorganic material is preferably made of a low melting point glass having a softening point of 300 to 1000 ° C.

In the exhaust system part of the present invention, when the amorphous inorganic material is composed of a low-melting glass having a softening point of 300 to 1000 ° C., the surface coating layer is formed on the surface of the base material by means of coating or the like. The surface coating layer can be formed relatively easily by heating after forming the layer of the raw material composition.
When the softening point of the low-melting glass is less than 300 ° C., the temperature of the softening point is too low. Therefore, during the heat treatment, the layer that becomes the surface coating layer easily flows due to melting, etc. On the other hand, when the softening point of the low-melting glass exceeds 1000 ° C., on the contrary, it is necessary to set the temperature of the heat treatment to be extremely high, so that the mechanical properties of the base material are deteriorated by heating. There is a fear. Moreover, the surface coating layer containing an amorphous inorganic material cannot follow the change in thermal expansion due to the temperature of the base material, which may cause cracks in the surface coating layer, causing cracks.

In the exhaust system component of the present invention, the low melting point glass is preferably a glass containing at least one of barium glass, boron glass, strontium glass, alumina silicate glass, soda zinc glass, and soda barium glass.

When low melting glass made of the above material is used for the exhaust system component, a surface coating layer having low thermal conductivity and heat resistance and durability can be formed on the surface of the substrate.

In the exhaust system component of the present invention, it is preferable that the base material is an exhaust pipe, and a surface covering material layer is formed inside the exhaust pipe.

When the surface coating layer of the present invention is formed inside the exhaust pipe in the exhaust system parts, an exhaust pipe having excellent heat insulation performance can be manufactured. Therefore, by using this exhaust pipe, the temperature can be raised to the catalyst activation temperature in a short time from the start of the engine, and the performance of the catalytic converter can be fully exhibited from the start of the engine.

FIG. 1 is a cross-sectional view schematically showing an exhaust system component of the present invention. FIG. 2 is a scanning electron microscope (SEM) photograph showing a longitudinal section of the surface coating layer constituting the exhaust system component according to the present invention. FIGS. 3A and 3B are cross-sectional views schematically showing another example of the exhaust system component of the present invention. FIG. 4 is an exploded perspective view schematically showing an automobile engine related to the exhaust system component of the present invention and an exhaust manifold connected to the automobile engine. 5A is a cross-sectional view of the automobile engine and the exhaust manifold shown in FIG. 4 taken along line AA, and FIG. 5B is a cross-sectional view of the exhaust manifold shown in FIG. 5A taken along line BB. It is.

(Detailed description of the invention)
Hereinafter, the present invention will be specifically described. However, the present invention is not limited to the following contents, and can be appropriately modified and applied without departing from the scope of the present invention.

Hereinafter, the exhaust system component of the present invention and the exhaust system component paint used for manufacturing the exhaust system component will be described.
First, the exhaust system component of the present invention will be described.
FIG. 1 is a cross-sectional view schematically showing an example of an exhaust system component of the present invention.
An exhaust system component 10 shown in FIG. 1 includes a base material 11 made of metal and a single surface coating layer 12 formed on the surface of the base material 11.

In the exhaust system component 10 shown in FIG. 1, the surface coating layer 12 formed on the surface of the base material 11 is dispersed inside the amorphous inorganic material layer 13 containing silica and the amorphous inorganic material layer 13. The particles 14 are composed of crystalline inorganic material particles 14 containing zirconia, and the reaction product particles 15 and pores 16 generated by the reaction between the crystalline inorganic material particles 14 and the amorphous inorganic material layer 13.
As shown in FIG. 1, reaction product particles and pores are dispersed in a plurality of sizes in the surface coating layer. Moreover, the reaction product particles are also present in the surface coating layer in various sizes and shapes, and similar shapes are not oriented in the same direction, but are present in random directions.

Examples of the material of the base material 11 constituting the exhaust system component 10 include metals such as stainless steel, steel, iron, and copper, or nickel alloys such as Inconel, Hastelloy, and Invar. As will be described later, the base material made of these metal materials has a surface expansion layer 12 and a metal base material 11 made of metal by bringing the thermal expansion coefficient close to that of the amorphous inorganic material layer 13 constituting the surface coating layer 12. It is possible to improve the adhesion.
Moreover, in order to improve the adhesiveness with the surface coating layer, a roughening treatment such as a sand blast treatment or a chemical may be applied to the surface of the substrate.

Surface roughness _{Rz JIS} of the surface of the substrate formed by the above roughening treatment, 1.5～20Myuemu is desirable. The surface roughness Rz _JIS of the roughened surface described above is a ten-point average roughness defined by JIS B 0601 (2001).
When the surface roughness Rz _{JIS of the} roughened surface of the exhaust system parts is less than 1.5 μm, the surface area of the base material becomes small, and it is difficult to obtain sufficient adhesion between the base material and the surface coating layer. Become. On the other hand, when the surface roughness Rz _{JIS of the} roughened surface of the base material of the exhaust system component exceeds 20 μm, it becomes difficult to form a surface coating layer on the surface of the base material. This is because when the surface roughness Rz _{JIS of the} roughened surface of the base material of the exhaust system component is too large, slurry (raw material composition for the surface coating layer) is formed in the uneven valley portion formed on the surface of the base material. It is thought that this is because a gap is formed in this portion without entering.
In addition, the surface roughness Rz _JIS of the roughened surface of the base material of the exhaust system component can be measured according to JIS B 0601 (2001) using Handy Surf E-35B manufactured by Tokyo Seimitsu Co., Ltd. .

In addition to a flat plate, a semi-cylinder, and a cylindrical shape, the shape of the outer edge of the cross section may be an arbitrary shape such as an ellipse or a polygon.
When the base material of the exhaust system part is a cylindrical body, the diameter of the base material may not be constant along the longitudinal direction, and the cross-sectional shape perpendicular to the length direction is not constant along the longitudinal direction. May be.

In the exhaust system part of the present invention, the desirable lower limit of the thickness of the substrate is 0.2 mm, the more desirable lower limit is 0.4 mm, the desirable upper limit is 10 mm, and the more desirable upper limit is 4 mm.
When the thickness of the base material of the exhaust system component is less than 0.2 mm, the strength of the exhaust system component is insufficient. In addition, if the thickness of the base material of the exhaust system component exceeds 10 mm, the weight of the exhaust system component increases, and it becomes difficult to mount the exhaust system component on a vehicle such as an automobile, for example.

The amorphous inorganic material constituting the surface coating layer 12 of the exhaust system part is preferably an amorphous inorganic material containing silica, and preferably contains 20% by weight or more of silica.
Since the amorphous inorganic material contains silica, it easily reacts with the particles 14 of the crystalline inorganic material containing zirconia dispersed in the amorphous inorganic material layer 13 to produce zircon containing silica. In particular, when 30% by weight or more of silica is contained, zircon is more easily generated.

Moreover, it is preferable that the said amorphous inorganic material is a low melting glass whose softening point is 300-1000 degreeC.
The type of the low melting point glass is not particularly limited, but soda lime glass, alkali-free glass, borosilicate glass, potash glass, crystal glass, titanium crystal glass, barium glass, boron glass, strontium glass, alumina silicate glass, Examples include soda zinc glass and soda barium glass.
These glasses may be used alone or in combination of two or more.

When the low melting point glass has a softening point in the range of 300 to 1000 ° C., the low melting point glass is melted and coated (coated) on the surface of the base material (metal material), and then heated and fired. By applying, the surface coating layer 12 can be easily formed on the surface of the base material made of metal, and the surface coating layer having excellent adhesion to the base material can be formed.

When the softening point of the low-melting glass is less than 300 ° C., the temperature of the softening point is too low, so that during the heat treatment, the surface coating layer easily flows due to melting or the like, and a layer with a uniform thickness is formed. On the other hand, when the softening point of the low melting point glass exceeds 1000 ° C., on the contrary, it is necessary to set the temperature of the heat treatment to be extremely high. May occur.
The softening point can be measured using a glass automatic softening point / strain point measuring device (SSPM-31) manufactured by Opt Corporation, for example, based on the method defined in JIS R 3103-1: 2001. it can.

Kind of the borosilicate glass is not particularly _limited, SiO ₂ -B ₂ O 3 -ZnO type _{glass, SiO 2 -B 2 O 3 -Bi} 2 O 3 system glass. The crystal glass is a glass containing PbO, the type is not particularly _limited, SiO 2 -PbO type _{glass, SiO 2 -PbO-B 2 O} 3 type _glass, SiO ₂ -B ₂ O 3 -PbO type glass Etc. Kind of the barium glass is not particularly limited, include BaO-SiO ₂ based glass or the like.
The amorphous inorganic material may be composed of only one kind of low-melting glass among the above-described low-melting glasses, or may be composed of a plurality of kinds of low-melting glasses.

The crystalline inorganic material contained in the surface coating layer of the exhaust system component has a softening point higher than the softening point of the amorphous inorganic material contained in the surface coating layer of the exhaust system component. Specifically, it is desirable that the crystalline inorganic material contained in the surface coating layer of the exhaust system component has a softening point of 950 ° C. or higher.

The crystalline inorganic material particles 14 dispersed in the amorphous inorganic material layer 13 constituting the surface coating layer 12 are zirconia or crystalline inorganic material particles containing zirconia.
Specific examples of inorganic materials containing zirconia include, for example, CaO-stabilized zirconia (5 wt% CaO—ZrO ₂ , 8 wt% CaO—ZrO ₂ , 31 wt% CaO—ZrO ₂ ), MgO stabilized zirconia (20 wt% MgO—ZrO ₂ ). ₂ , 24 wt% MgO—ZrO ₂ ), Y ₂ O ₃ stabilized zirconia (6 wt% Y ₂ O ₃ —ZrO ₂ , 7 wt% Y ₂ O ₃ —ZrO ₂ , 8 wt% Y ₂ O ₃ —ZrO ₂ , 10 wt% _{Y 2 O 3 -ZrO 2, 12wt} % Y 2 O 3 -ZrO 2, 20wt% Y 2 O 3 -ZrO 2), zircon _{(ZrO 2 -33wt% SiO 2)} , CeO stabilized zirconia, and the like.
Among these, Y ₂ O ₃ -stabilized zirconia, CaO-stabilized zirconia, and MgO-stabilized zirconia having excellent heat resistance and corrosion resistance and a thermal conductivity at 25 ° C. of 4 W / mK or less are preferable.

It is desirable that the crystalline inorganic material particles 14 contain 20% by weight or more of zirconia. When 20% by weight or more of zirconia is contained, the reaction product particles are excellent in heat resistance and react with silica in the amorphous inorganic material to include zirconia and silica from the surface of the particles 14 of the crystalline inorganic material. It is because it is easy to precipitate.

When the content of zirconia is less than 20% by weight, the reaction product particles 15 with the amorphous inorganic material layer 13 cannot be sufficiently grown, and the ability to prevent the movement of the pores 16 is reduced. The mechanical strength of the surface coating layer 12 is reduced.
It is more desirable that the crystalline inorganic material particles 14 contain 50% by weight or more of zirconia.

The average particle size of the crystalline inorganic material particles 14 is preferably 0.1 to 150 μm. When the average particle size of the crystalline inorganic material particles 14 is 0.1 to 150 μm, even if the surface coating layer 12 is heated to a high temperature by the crystalline inorganic material particles 14, the pores 16 are formed by the crystalline inorganic material particles 14. Movement is hindered and high heat insulation can be maintained.

If the average particle diameter of the crystalline inorganic material particles 14 is less than 0.1 μm, it becomes difficult to inhibit the movement of the pores 16, and further, since the zirconia content is small, it is difficult to maintain high heat resistance after drying. . On the other hand, when the average particle diameter of the particles 14 of the crystalline inorganic material exceeds 150 μm, there are many places where the distance between the surface of the surface coating layer 12 and the particles is short, and cracks are easily generated on the surface even with a slight stress such as bending. Become.
The average particle diameter of the particles 14 of the crystalline inorganic material is more preferably 1 to 50 μm. In this range, in addition to high heat resistance and prevention of cracks, the reaction product particles tend to have a shape strong against external loads. That is, the needle shape of the reaction product particles is likely to be thick, and is not easily broken without breaking.

The ratio of the average pore diameter of the pores 16 to the average particle diameter of the particles 14 of the crystalline inorganic material (average particle diameter of the crystalline inorganic material particles / average pore diameter of the pores) is 0.1 to 10.
When the ratio of the average pore size of the pores 16 to the average particle size of the particles 14 of the crystalline inorganic material (average particle size of the crystalline inorganic material particles / average pore size of the pores) is in the above range, the surface coating layer 12 The crystalline inorganic material particles 14 become obstacles to the movement of the pores 16 when the temperature becomes high, and the movement of the pores 16 is hindered, and it is possible to prevent the heat insulation performance from being deteriorated due to the coalescence of the pores 16. .

When the above ratio (average particle diameter of the crystalline inorganic material particles / average pore diameter of the pores) is less than 0.1, the ratio of the average particle diameter of the crystalline inorganic material particles compared to the average pore diameter of the pores Therefore, when the temperature becomes high, the effect of inhibiting the movement of the pores is small, the coalescence of the pores easily proceeds, and it becomes difficult to maintain high heat insulation.

On the other hand, when the above ratio (average particle diameter of the crystalline inorganic material particles / average pore diameter of the pores) exceeds 10, the ratio of the average particle diameter of the crystalline inorganic material particles compared to the average pore diameter of the pores is Too big. That is, in this case, the crystalline inorganic material particles 14 may crush and destroy the pores 16, which may reduce the mechanical strength and heat insulation performance of the surface coating layer 12.
The ratio of the average pore diameter of the pores 16 to the average particle diameter of the particles 14 of the crystalline inorganic material (average particle diameter of the crystalline inorganic material particles / average pore diameter of the pores) is preferably 0.5 to 5.

In addition, since the crystalline inorganic material includes zirconia and the amorphous inorganic material includes silica, the amorphous inorganic material layer and the crystal are formed in the amorphous inorganic material layer when forming the surface coating layer. Reactive inorganic particles react to produce and precipitate reaction product particles made of zircon or the like.

FIG. 2 is a scanning electron microscope (SEM) photograph showing a longitudinal section of the surface coating layer constituting the exhaust system component according to the present invention. This SEM photograph is an SEM photograph showing the reaction product particles extending in a needle shape generated by the reaction between the crystalline inorganic material and the amorphous inorganic material.
In the SEM photograph shown in FIG. 2, reaction product particles 15 extending in a needle shape from the surface of the crystalline inorganic material particles 14 in the amorphous inorganic material layer 13 can be observed.
The shape of the reaction product particles 15 shown in FIG. 2 is needle-like, but depending on the reaction conditions, it is crushed. When the reaction product particles 15 are generated, the size of the particles in the amorphous inorganic material layer 13 becomes the total size of the crystalline inorganic material particles 14 and the reaction product particles 15. In addition, it is possible to more effectively prevent the plurality of pores 16 from being combined.

In the exhaust system component of the present invention, it is desirable that 5 to 50% by weight of the crystalline inorganic material particles 14 are in contact with the pores having a pore diameter of 0.1 to 50 μm.
When the pores 16 are in contact with and adhered to the crystalline inorganic material particles 14, the pores are difficult to move away from the crystalline inorganic material particles 14 even at high temperatures, and the surface coating layer 12 is highly insulated. Sex can be maintained. In the exhaust system component of the present invention, it is more preferable that 20 to 40% by weight of the crystalline inorganic material particles 14 are in contact with the pores having a pore diameter of 1 to 50 μm.

When the crystalline inorganic material particles 14 in contact with the pores 16 are less than 5% by weight, the crystalline inorganic material particles 14 do not contribute to the suppression of the movement of the pores 16, and the coalescence of the pores 16 occurs and the heat insulation performance is lowered. Resulting in. On the other hand, if the crystalline inorganic material particles 14 in contact with the pores 16 exceed 50% by weight, the content of the crystalline inorganic material particles 14 in the surface coating layer 12 is too large. The mechanical strength or heat insulation performance is reduced.

Assuming that the pores 16 of less than 0.1 μm are in contact with the crystalline inorganic material particles 14, the smaller the pores, the more the number of pores in contact therewith. An increase in the number of pores means that the number of cracks such as cracks in the surface coating layer increases, resulting in problems such as deterioration in quality and mechanical strength. On the other hand, when the pores 16 having a pore diameter of more than 50 μm are in contact with the crystalline inorganic material particles 14, the pores 16 are often already joined by movement. As described above, when the pores 16 having a large pore diameter are formed in the surface coating layer 12, since the solid portion of the surface coating layer 12 is small, the mechanical properties of the surface coating layer 12 are deteriorated. Moreover, since the heat dissipation effect is accelerated | stimulated by the convective heat transfer and the radiant heat transfer in such a large pore 16, the heat insulation property falls.

In this case, as described above, the pores 16 may be in contact with the pores 16 via the reaction product particles 15 extending from the crystalline inorganic material particles 14.
When the reaction product particles 15 are generated, since the reaction product particles 15 extend from the surface of the crystalline inorganic material particles 14 toward the periphery thereof, the reaction product particles 15 easily come into contact with the pores 16 and have an opportunity to contact the pores 16. Will increase. For this reason, it becomes difficult for the pores 16 to move, and it is possible to more effectively prevent the plurality of pores 16 from being combined.

The average particle size of the reaction product particles 15 is desirably 0.01 to 25 μm. When the average particle diameter of the reaction product particles 15 is 0.01 to 25 μm, the reaction product particles 15 extending from the crystalline inorganic material particles 14 move pores even when the surface coating layer 12 is heated to a high temperature. Can be prevented, so that coalescence of the pores 16 can be prevented. The average particle diameter of the reaction product particles 15 is more preferably 0.1 to 15 μm. In this range, the tip of the reaction product particles 15 tends to be thick and the mechanical strength is strong.
Here, the average particle size of the reaction product particles is the reaction product particle size that is the distance from the tip of the reaction product particle generated from one particle to the tip, and 100 different reaction product particle sizes are measured. Then, the averaged particle diameter is defined as the average particle diameter of the reaction product particles.

When the average particle size of the reaction product particles 15 is less than 0.01 μm, the effect of preventing the movement of the pores 16 is small. Further, if the average particle diameter of the reaction product particles 15 exceeds 25 μm, the reaction product particles 15 existing in the surface coating layer 12 are large in size, so that it becomes necessary to make the surface coating layer 12 thicker than necessary. As a result, the bending stress of the surface coating layer 12 increases, so that cracks are likely to occur.

As described above, in the amorphous inorganic material layer 13 constituting the surface coating layer 12, pores due to the pore former contained in the exhaust system component paint as a raw material are dispersed, The porosity of the coating layer 12 is desirably 30 to 80%.
When the porosity of the surface coating layer 12 is 30 to 80% and the pores 16 are well dispersed, heat transfer in the surface coating layer 12 can be effectively blocked by the pores 16 and good. Can maintain a good thermal insulation.

When the porosity of the surface coating layer 12 is less than 30%, the proportion of the pores 16 is too small, and thus the heat insulating property is deteriorated. On the other hand, when the porosity of the surface coating layer 12 exceeds 80%, the porosity 16 Therefore, for example, the pores 16 are easily exposed on the surface of the surface coating layer 12 and it is difficult to maintain the porosity, and the distance between the pores 16 is reduced, and the pores 16 are combined. It becomes easy to maintain high heat insulation when the surface coating layer 12 becomes high temperature.

The average pore diameter of the pores 16 in the surface coating layer 12 is desirably 0.1 to 50 μm. When the average pore diameter of the pores 16 in the surface coating layer 12 is 0.1 to 50 μm, heat transfer in the surface coating layer 12 can be effectively prevented by the pores 16, and the high thermal insulation of the surface coating layer 12. Can be maintained. As the average pore diameter of the pores 16 in the surface coating layer 12 is smaller, heat transfer by radiant heat transfer and convective heat transfer in the pores can be reduced. 1 to 50 μm is more desirable, and 1 to 5 μm is even more desirable. When the average pore diameter is in the range of 1 to 5 μm, the heat transfer in the pores can be reduced most.

If the average pore diameter of the pores 16 is less than 0.1 μm, it is technically difficult to form the pores 16 having such a size, and in order to form such pores 16, a very small pore former Since it is necessary to use a special material such as a material, the material cost increases rapidly, which is not preferable.
On the other hand, if the pore diameter exceeds 50 μm, the pores 16 are often already joined by movement. As described above, when the pores 16 having a large pore diameter are formed in the surface coating layer 12, since the solid portion of the surface coating layer 12 is small, the mechanical properties of the surface coating layer 12 are deteriorated. In addition, the pores 16 having a diameter exceeding 100 μm have a reduced heat insulation property because the heat dissipation effect is promoted by convective heat transfer and radiation heat transfer in the pores.

The thickness of the surface coating layer 12 is desirably 50 to 2000 μm, and more desirably 250 to 2000 μm.
When the thickness of the surface coating layer 12 is less than 50 μm, the thickness of the surface coating layer 12 is too thin, so that sufficient heat insulation performance cannot be exhibited when used as an exhaust system component. On the other hand, when the thickness of the surface coating layer 12 exceeds 2000 μm, the surface coating layer 12 is too thick, and therefore when exposed to thermal shock, the surface coating layer 12 is exposed to the bonding surface with the base material 11 and the atmosphere. The temperature difference from the existing surface is likely to be large, and the surface coating layer 12 is easily destroyed.

The thermal conductivity of the surface coating layer 12 at room temperature is preferably 0.05 to 2 W / mK.
When the thermal conductivity of the surface coating layer 12 at room temperature is 0.05 to 2 W / mK, the exhaust system component 10 of the present invention is excellent in heat insulation, and the thermal conductivity is difficult to increase even at high temperatures. Further, it is possible to prevent the temperature of exhaust gas or the like from decreasing.
It is not easy to realize the surface coating layer 12 having a thermal conductivity of the surface coating layer 12 at room temperature of less than 0.05 W / mK in consideration of the balance between both the technical viewpoint and the economic viewpoint. If the thermal conductivity of the coating layer 12 at room temperature exceeds 2 W / mK, the heat retention of the exhaust pipe in the low temperature region becomes insufficient. For example, when used in the exhaust pipe, the temperature of the catalytic converter is the catalyst activation temperature. It takes a long time to reach the point, which is not desirable.
The thermal conductivity at room temperature of the surface coating layer of the exhaust system component can be measured by a laser flash method.

In the exhaust system component of the present invention, even when a semi-cylindrical base material or a cylindrical base material is used, the surface coating layer 12 in the exhaust system component 10 shown in FIG. Has been. The surface coating layer 12 may be formed on both surfaces of the substrate 11.

Even when the surface coating layer 12 is formed on both surfaces of the substrate 11, the thickness of the surface coating layer 12 is desirably 50 to 2000 μm.

Next, the method for manufacturing the exhaust system component of the present invention will be described.
First, the exhaust system component paint used in the manufacture of the exhaust system component of the present invention will be described. The exhaust system component paint is a raw material composition used for manufacturing exhaust system components.

The exhaust system paint according to the present invention includes amorphous inorganic material containing silica, crystalline inorganic material particles containing zirconia, and pore former particles.
The average particle size of the crystalline inorganic material particles is 0.1 to 150 μm,
The weight of the crystalline inorganic material particles with respect to 100 parts by weight of the amorphous inorganic material is 30 to 180 parts by weight,
The average particle diameter of the pore former particles is 0.1 to 25 μm,
The weight of the pore former particles is 0.001 to 1 part by weight with respect to 100 parts by weight of the amorphous inorganic material.

By using the paint for exhaust system parts of the present invention, the exhaust system parts of the present invention described above can be manufactured, but the use is not limited to the manufacture of the exhaust system parts, and a coating film is formed. It may be used for other purposes.
As described above, the exhaust system component paint includes an amorphous inorganic material containing silica, particles of a crystalline inorganic material containing zirconia, and particles of a pore former.

Since the type, material, material, characteristics and the like of the amorphous inorganic material containing silica have been described in the exhaust system parts of the present invention, they will be omitted. As described above, when preparing the paint for exhaust system parts of the present invention, the amorphous inorganic material powder is used. When preparing the paint for exhaust system parts of the present invention, after preparing each raw material, wet pulverization is performed, but the amorphous inorganic material powder is first adjusted to an appropriate particle size, After the raw materials are prepared, the desired particle size is obtained by wet grinding.
Amorphous inorganic material is applied to the surface of the substrate, fired, and then melted to form a coating film (layer of amorphous inorganic material). Therefore, it is not necessary to strictly control the particle size of the amorphous inorganic material. However, it is necessary that the particles of the amorphous inorganic material are uniformly dispersed in the paint for exhaust system parts.
In this respect, the final average particle size after wet pulverization of the amorphous inorganic material is preferably 0.1 to 100 μm, and more preferably 1 to 20 μm. In the range of 1 to 20 μm, it is presumed that there is little influence of electricity charged on the particle surface, but the particles are easily dispersed uniformly.

As for the crystalline inorganic material containing zirconia, the type, material, material, characteristics thereof, and the like have been described in the exhaust system parts of the present invention, and therefore will be omitted. When preparing the paint for exhaust system parts of the present invention, each raw material is prepared and then wet pulverization is performed. In the case of a crystalline inorganic material, a material first adjusted to an appropriate particle size is used. By pulverization, the desired particle size is obtained.
The final average particle size after wet pulverization of the crystalline inorganic material is preferably 0.1 to 150 μm.

The average particle size of the particles of the crystalline inorganic material after the wet pulverization is 0.1 to 150 μm, and the particle size of the crystalline inorganic material dispersed in the amorphous inorganic material layer after forming the surface coating layer is It is considered that the particle diameter of the crystalline inorganic material after wet pulverization before forming the layer of the crystalline inorganic material is almost the same. The average particle diameter of the particles of the crystalline inorganic material dispersed in the amorphous inorganic material layer after forming the surface coating layer is 0.1 to 150 μm. The movement of the pores 16 is hindered by the particles 14 of the equipment, and high heat insulation can be maintained. As for the average particle diameter of the particle | grains of the crystalline inorganic material after wet grinding, it is more desirable that it is 1-50 micrometers.

If the average particle diameter of the crystalline inorganic material particles 14 is less than 0.1 μm, it becomes difficult to prevent the movement of the pores 16, and furthermore, since the amount of zirconia is small, it is difficult to maintain high heat resistance after drying. . On the other hand, if the average particle diameter of the crystalline inorganic material particles 14 exceeds 150 μm, the distance between the surface of the surface coating layer 12 and the crystalline inorganic material particles 14 is short, and the surface can be obtained even with a slight stress such as bending. Cracks are likely to occur. In particular, when the average particle diameter of the crystalline inorganic material particles 14 exceeds 500 μm, the tendency becomes remarkable.

The weight of the crystalline inorganic material particles with respect to 100 parts by weight of the amorphous inorganic material is set to 30 to 180 parts by weight.
By using the particles of the crystalline inorganic material in such a weight ratio with respect to the amorphous inorganic material, the crystalline inorganic material is contained in the amorphous inorganic material layer constituting the manufactured exhaust system part. The particles can be dispersed at an appropriate ratio to ensure the heat resistance and heat insulation properties of the surface coating layer. The weight of the crystalline inorganic material particles with respect to 100 parts by weight of the amorphous inorganic material is preferably set to 60 to 150 parts by weight.

When the weight of the crystalline inorganic material particles relative to 100 parts by weight of the amorphous inorganic material is less than 30 parts by weight, the amount of the crystalline inorganic material particles dispersed in the amorphous inorganic material layer is small. The pores dispersed inside in the sound range are easy to move, and the heat insulation is reduced.
On the other hand, when the weight of the particles of the crystalline inorganic material exceeds 180 parts by weight with respect to 100 parts by weight of the amorphous inorganic material, the amount of the amorphous inorganic material is relatively reduced, and the formation of the coating film (the surface coating layer) Formation) becomes difficult, and peeling from the substrate tends to occur.

The pore former in the paint for exhaust system parts of the present invention will be described.
The pore former is used to form pores in the surface coating layer when a coating film is formed on the surface of the base material using the paint for exhaust system parts and then the surface coating layer is formed by heating and baking. It has been.

As the pore former, for example, balloons that are fine hollow spheres composed of oxide ceramics, spherical acrylic particles, carbon such as graphite, carbonates, foaming agents, and the like can be used. The formed surface coating layer desirably has a high heat insulating performance. For that purpose, it is desirable that pores having a small diameter are uniformly dispersed.

From such a viewpoint, the pore former is preferably carbon, carbonate, or a foaming agent.
Examples of the carbonate and the foaming agent include CaCO ₃ , BaCO ₃ , NaHCO ₃ , Na ₂ CO ₃ , (NH ₄ ) ₂ CO _{3 and the} like.
Further, among these pore formers, carbon such as graphite is preferable. This is because carbon can be dispersed as fine particles in a paint for exhaust system parts by a process such as pulverization and can be decomposed by heating and baking to form pores having a suitable pore diameter.

From the above viewpoint, the average particle diameter of the pore former particles is set to 0.1 to 25 μm.
Since the average particle diameter of the pore-forming material particles is 0.1 to 25 μm, the diameter of the pores in the formed amorphous inorganic material layer can be 0.1 to 50 μm. The average particle size of the pore former particles is desirably set to 0.5 to 10 μm.

When the average particle diameter of the pore former is less than 0.1 μm, it is difficult to disperse the pore former in the exhaust system component paint, and as a result, the amorphous inorganic material to be formed When the degree of dispersion of the pores in the layer decreases and the temperature becomes high, the pores are easily united. On the other hand, when the average particle diameter of the pore former particles exceeds 25 μm, the pore diameter formed in the amorphous inorganic material layer becomes too large, and the heat insulating property of the amorphous inorganic material layer is increased. Decreases.

The weight of the pore former particles with respect to 100 parts by weight of the amorphous inorganic material is set to 0.001 to 1 part by weight. Since the weight of the pore-forming material particles with respect to 100 parts by weight of the amorphous inorganic material is set to 0.001 to 1 part by weight, it is well dispersed in the exhaust system paint and applied to the surface of the base material. When the film is formed and the surface coating layer is formed by heating and baking, the surface coating layer in which pores are well dispersed can be formed. The weight of the pore former particles with respect to 100 parts by weight of the amorphous inorganic material is preferably set to 0.005 to 0.5 parts by weight.

If the weight of the pore-forming material particles is less than 0.001 part by weight with respect to 100 parts by weight of the amorphous inorganic material, the surface coating layer exhibits good heat insulation properties because the proportion of pores in the surface coating layer is too small. On the other hand, if the weight of the pore-forming material particles exceeds 1 part by weight with respect to 100 parts by weight of the amorphous inorganic material, the ratio of the pore-forming material is too large, and thus the surface coating layer formed It becomes difficult to disperse the pores well, large pores are easily formed, and the surface coating layer cannot exhibit good heat insulating properties.

In the exhaust system component paint of the present invention, a dispersion medium, an organic binder, and the like can be blended in addition to the amorphous inorganic material, the crystalline inorganic material, and the pore former.
Examples of the dispersion medium include water and organic solvents such as methanol, ethanol, and acetone. The mixing ratio of the mixed powder or the amorphous inorganic material powder and the dispersion medium contained in the exhaust system paint is not particularly limited. For example, with respect to 100 parts by weight of the amorphous inorganic material powder The dispersion medium is preferably 50 to 150 parts by weight. It is because it becomes a viscosity suitable for apply | coating to a base material.
As an organic binder which can be mix | blended with the said coating material for exhaust system components, polyvinyl alcohol, methylcellulose, ethylcellulose, carboxymethylcellulose etc. can be mentioned, for example. These may be used alone or in combination of two or more.
Moreover, you may use a dispersion medium and an organic binder together.

Next, the preparation of the above-described exhaust system component paint and a method for manufacturing the exhaust system component using the same will be described.

(1) Step of preparing a base material made of metal A base material made of metal (hereinafter also referred to as a metal base material or a metal material) is used as a starting material. First, a cleaning process is performed to remove impurities on the surface of the metal base material. I do.
The cleaning process is not particularly limited, and a conventionally known cleaning process can be used. Specifically, for example, a method of performing ultrasonic cleaning in an alcohol solvent can be used.

In addition, after the above cleaning treatment, the surface of the metal substrate is roughened to increase the specific surface area of the metal substrate surface or adjust the surface roughness of the metal substrate as necessary. Processing may be performed. Specifically, for example, a roughening process such as a sandblast process, an etching process, or a high temperature oxidation process may be performed. These may be used alone or in combination of two or more.
You may perform a washing process after this roughening process.

(2) Step of forming surface coating layer First, a crystalline inorganic material, an amorphous inorganic material, a pore former, and the like are mixed to prepare an exhaust system paint.
Specifically, for example, a crystalline inorganic material powder and an amorphous inorganic material powder are prepared to have a predetermined particle size, shape, etc., and each powder is dry-mixed at a predetermined blending ratio. A mixed powder is prepared, water is further added, and wet mixing is performed with a ball mill to prepare an exhaust system paint.
Here, the mixing ratio of the mixed powder and water is not particularly limited, but is preferably about 100 parts by weight of water with respect to 100 parts by weight of the mixed powder. It is because it becomes a viscosity suitable for apply | coating to a metal base material. In addition, as described above, a dispersion medium such as an organic solvent, an organic binder, and the like may be blended in the exhaust system component paint as necessary.

(3) Next, a paint for exhaust system parts is coated on the surface of the metal substrate.
As a method for coating the exhaust system component paint for the surface coating layer, for example, spray coating, electrostatic coating, inkjet, transfer using a stamp or roller, brush coating, or electrodeposition coating is used. Can be used.
Moreover, you may coat the said coating material for exhaust system components by immersing the said metal base material in the coating material for exhaust system components.

(4) Subsequently, the metal substrate coated with the exhaust system component paint is fired.
Specifically, the surface coating layer is formed by drying and heating and firing the metal substrate coated with the exhaust system component paint. At this time, the pore former is decomposed by the above baking or foamed and changed into a gas, and pores are formed in the surface coating layer. The pore former is preferably changed to a gas at 600 to 1000 ° C.
The firing temperature is preferably set to be equal to or higher than the softening point of the amorphous inorganic material, and is preferably 700 ° C. to 1100 ° C. although it depends on the type of the blended amorphous inorganic material and the type of pore former. By setting the firing temperature to a temperature equal to or higher than the softening point of the amorphous inorganic material, the metal substrate and the amorphous inorganic material can be firmly adhered, and a surface coating layer that is firmly adhered to the metal substrate is formed. Because it can be done.

By the above procedure, the exhaust system component 10 shown in FIG. 1 as an example of the exhaust system component of the present invention can be manufactured.

FIG. 3A is a cross-sectional view schematically showing a member (hereinafter referred to as a half member) obtained by cutting a cylindrical body of a base material constituting an exhaust system component in half, and FIG. FIG. 3 is a cross-sectional view schematically showing an exhaust system component when the substrate is a cylindrical body.
In the exhaust system component 30 shown in FIG. 3B, a surface coating layer 32 having the same configuration as the surface coating layer shown in FIG. 1 is formed inside a base material 31 made of a cylindrical body like an exhaust pipe. Yes.
For this reason, when the surface coating layer is formed on the exhaust pipe, the exhaust pipe has excellent heat insulation performance. Therefore, by using this exhaust pipe, the temperature can be raised to the catalyst activation temperature in a short time from the start of the engine, and the performance of the catalytic converter can be fully exhibited from the start of the engine.

An example of a method for manufacturing an exhaust system component in which such a base material is a cylindrical body and a surface coating layer is formed on the inner surface of the cylindrical body is shown below.
When the exhaust system component (cylindrical body) 30 shown in FIG. 3 (b) is long, it is not impossible but difficult to form a surface coating layer on the entire interior. An exhaust system part (half member) 20 (see FIG. 3A) obtained by cutting the cylindrical body of the base material constituting the part in half is used.
In this case, after forming the amorphous inorganic material layer 23 constituting the surface coating layer 22 on the surface of the base material 21, the two exhaust system parts (half member) 20 are combined to form the inner surface of the base material 31. An exhaust system component 30 made of a cylindrical body having a surface coating layer 32 formed thereon is produced.

First, as a metal substrate, a first half member and a second half member obtained by cutting a cylindrical body in half are prepared. Next, for the first half member and the second half member, a coating for exhaust system parts is coated on the inner surface having a small area. Subsequently, a surface covering layer is formed on the surfaces of the first half member and the second half member by performing a firing process on the first half member and the second half member, 1 half member and 2nd half member are joined by welding etc., and it is set as a cylindrical body.
According to the above procedure, an exhaust system component in which the metal substrate is a cylindrical body and the surface coating layer is formed on the inner surface of the cylindrical body can be manufactured.

Further, an exhaust system component in which the metal substrate is a cylindrical body and the surface coating layer is formed on the outer surface of the cylindrical body may be manufactured. In this case, a cylindrical metal substrate may be used as the metal substrate, or the first half member and the second half member as described above may be used.

The effects of the exhaust system parts and the paint for exhaust system parts of the present invention will be listed below.
(1) In the exhaust system component of the present invention, a surface coating layer is formed on the surface of a base material made of metal. The surface coating layer includes an amorphous inorganic material layer containing silica, crystalline inorganic material particles containing zirconia dispersed inside the amorphous inorganic material layer, crystalline inorganic material particles, and non-crystalline material. It consists of reaction product particles and pores produced by the reaction with the crystalline inorganic material layer, and since the pores exist in the surface coating layer, the pores prevent heat conduction inside the solid, and excellent heat insulation properties Is obtained.

(2) In the exhaust system component of the present invention, the particles of the crystalline inorganic material are dispersed in the surface coating layer, and the ratio of the average pore diameter of the pores to the average particle diameter of the particles of the crystalline inorganic material (described above) Since the average particle diameter of the crystalline inorganic material particles / the average pore diameter of the pores is 0.1 to 10, when the surface coating layer is heated, the crystalline inorganic material particles move through the pores. It is possible to prevent the movement of pores from being hindered and the heat insulation performance from being deteriorated due to coalescence of the pores. Therefore, the high thermal insulation of the surface coating layer can be maintained over a long period of time.

(3) In the exhaust system component of the present invention, the particles of the crystalline inorganic material in the surface coating layer serve to mechanically strengthen the surface coating layer and prevent coalescence of pores. It is possible to prevent the occurrence of cracks and the like due to the deterioration of the mechanical strength of the surface coating layer, and to prevent the extension of cracks even if the cracks or the like occur.

(4) In the exhaust system component of the present invention, the surface coating layer contains crushed or acicular reaction product particles produced by a reaction between the crystalline inorganic material particles and the amorphous inorganic material layer. Therefore, the pore movement is inhibited by the reaction product particles, and the surface coating layer can maintain high heat insulation performance.
Thus, since the exhaust system component of this invention is excellent in heat insulation and heat resistance, it can be used conveniently as exhaust system components, such as an exhaust pipe, for example.

(5) In the exhaust system part of the present invention, 5 to 50% by weight of the crystalline inorganic material particles are in contact with the pores having a pore diameter of 0.1 to 50 μm. The pores hardly move away from the particles of the crystalline inorganic material. As a result, coalescence of the pores can be prevented, and the high thermal insulation of the surface coating layer can be maintained.

(6) In the exhaust system component of the present invention, the crystalline inorganic material contained in the surface coating layer contains 20% by weight or more of zirconia.
Zirconia is a crystalline inorganic material with excellent heat resistance. Therefore, even when the surface coating layer of the exhaust system component is exposed to a high temperature, since the zirconia existing in the surface coating layer of the exhaust system component is difficult to soften, the surface coating layer is peeled off from the base material made of metal. This can be prevented.
Zirconia is also a crystalline inorganic material with excellent corrosion resistance. Therefore, when the surface coating layer of the exhaust system component is directly exposed to high-temperature exhaust gas, the surface coating of the exhaust system component is caused by nitrogen oxide (NOx) and / or sulfur oxide (SOx) contained in the exhaust gas. It is possible to prevent the layer from corroding.

(7) In the exhaust system component of the present invention, the thickness of the surface coating layer is 50 to 2000 μm.
When the thickness of the surface coating layer is the above-described thickness, the ratio of the size of the pores to the thickness of the surface coating layer and the size of the crystalline inorganic material is in a suitable range, and the heat insulation performance and mechanical properties are further improved. It can be maintained well.

(8) In the exhaust system component of the present invention, the thermal conductivity of the surface coating layer at room temperature is 0.05 to 2 W / mK.
When the thermal conductivity at room temperature of the surface coating layer of the exhaust system component is 0.05 to 2 W / mK, the rate at which heat is conducted and transferred to the outside of the exhaust system component through the surface coating layer can be reduced. . Therefore, the heat insulation of the exhaust system parts can be further increased.

(9) In the exhaust system component of the present invention, the porosity of the surface covering material layer is 30 to 80%, and the average pore diameter of the pores is 0.1 to 50 μm.
In order to maintain the heat insulating property of the surface coating layer due to the pores contained in the surface coating layer, the porosity and the average pore diameter of the pores are in an appropriate range, and as a result, the exhaust system component of the present invention has good performance. Thermal insulation can be maintained.

(10) The exhaust system component paint according to the present invention, the exhaust system component paint includes an amorphous inorganic material containing silica, a crystalline inorganic material particle containing zirconia, and a pore former particle, The average particle size of the particles of the crystalline inorganic material is 0.1 to 150 μm, the weight of the particles of the crystalline inorganic material with respect to 100 parts by weight of the amorphous inorganic material is 30 to 180 parts by weight, The average particle size of the particles of the material is 0.1 to 25 μm, and the weight of the pore former particles is 0.001 to 1 part by weight with respect to 100 parts by weight of the amorphous inorganic material. It can be suitably used as a paint used for exhaust system parts having

(Example)
Examples of exhaust system parts and paints for exhaust system parts of the present invention will be described below more specifically. In addition, this invention is not limited only to these Examples.

Example 1
(1) Preparation of base material As a base material made of a metal, a plate-shaped stainless steel base material (made of SUS430) having a length of 40 mm, a width of 40 mm and a thickness of 1.5 mm is used as a material, and ultrasonic cleaning is performed in an alcohol solvent Subsequently, the surface (both sides) of the substrate was roughened by sandblasting. The sandblast treatment was performed for 10 minutes using # 100 Al ₂ O ₃ abrasive grains.
When the surface roughness of the metal substrate was measured using a surface roughness measuring machine (manufactured by Tokyo Seimitsu Co., Ltd., Handy Surf E-35B), the surface roughness of the metal substrate was Rz _JIS = 8.8 μm. there were.
A flat substrate was produced by the above treatment.

(2) Preparation of paint for exhaust system part for surface coating layer As powder of amorphous inorganic material, K4006A-100M (Bi ₂ O ₃ -B ₂ O ₃ system glass, softening point 770 ° C.) 35 manufactured by Asahi Glass Co., Ltd. A weight part was prepared. In addition, the compounding ratio with respect to the whole coating material for exhaust system parts of an amorphous inorganic material is 34 weight%. The said mixture ratio shows the ratio with respect to the whole weight of the coating material for exhaust system components containing water etc. in percentage. The amorphous inorganic material powder had an average particle size of 15 μm and contained 25% by weight of silica.
Further, 20 parts by weight of yttria-stabilized zirconia containing 8% by weight of yttria was prepared as particles of the crystalline inorganic material. The average particle size of the crystalline inorganic material particles was 25 μm.

Furthermore, 0.5 weight part of methyl cellulose (product name: METOLOSE-65SH) manufactured by Shin-Etsu Chemical Co., Ltd. was prepared as an organic binder.
In preparation of the exhaust system component paint used for forming the surface coating layer, 46 parts by weight of water was further added, and the exhaust system component paint was prepared by wet mixing with a ball mill.
In preparing the exhaust system paint, 0.005 part by weight of carbon was added as a pore former. The average particle diameter of the pore former was 1 μm.
Table 1 shows the application target, the coated surface, the type and average particle size and mixing ratio of the crystalline inorganic material, the mixing ratio of the amorphous inorganic material, and the average particle size and mixing ratio of the pore former.

Here, when the crystalline inorganic material, the amorphous inorganic material, and the pore former can be taken out while maintaining the shape as a particle, each particle is measured by an apparatus using a laser diffraction method (SALD-300V manufactured by Shimadzu Corporation). What is necessary is just to measure a diameter, and an average particle diameter should just measure 100 particle | grains using the said apparatus, and should just make the average value of the particle diameter into an average particle diameter.
In addition, when a surface coating layer is formed on the exhaust pipe and the crystalline inorganic material and reaction product particles cannot be taken out while maintaining the shape, the particle diameter is measured by using the following three-dimensional measurement X-ray CT apparatus. What is necessary is just to calculate an average particle diameter from the data.
In this case, a sample obtained by cutting out the surface coating layer to a size of 3.1 mm is measured with a three-dimensional measurement X-ray CT apparatus (TDM1000-IS / SP, manufactured by Yamato Scientific Co., Ltd.), and is measured with three-dimensional volume rendering software (NVS). The particle size can be measured by performing image processing with (VG-Studio MAX) manufactured by Nippon Visual Science Co., Ltd. Here, with respect to the particle diameter, two points are taken for one particle surface, and the value having the largest linear distance between the two points is defined as the particle diameter. 100 samples may be collected from the surface coating layer by the measurement method, the particle diameter may be measured, and the average value of the particle diameters may be defined as the average particle diameter.

(3) Manufacture of exhaust system components The prepared exhaust system component paint was applied to one surface of a flat substrate by a spray coating method and dried in a dryer at 70 ° C for 20 minutes. Subsequently, a surface coating layer having a thickness of 500 μm was formed by heating and baking in air at 850 ° C. for 90 minutes.

(Examples 2 to 5)
The type of base material to be coated, the type and average particle diameter of the crystalline inorganic material to be used, the mixing ratio, the mixing ratio of the amorphous inorganic material, the average particle diameter and mixing ratio of the pore former, the surface coating layer to be formed A surface coating layer was formed in the same manner as in Example 1 except that the thickness was changed as shown in Tables 1 and 2. Table 1 shows the application target, the coated surface, the type and average particle size and mixing ratio of the crystalline inorganic material, the mixing ratio of the amorphous inorganic material, and the average particle diameter and mixing ratio of the pore former.

(Comparative Examples 1-4 and Reference Example 1)
The type of base material to be coated, the type and average particle diameter of the crystalline inorganic material to be used, the mixing ratio, the mixing ratio of the amorphous inorganic material, the average particle diameter and mixing ratio of the pore former, the surface coating layer to be formed A surface coating layer was formed in the same manner as in Example 1 except that the thickness was changed as shown in Tables 1 and 2. Table 1 shows the application target, the coated surface, the type and average particle size and mixing ratio of the crystalline inorganic material, the mixing ratio of the amorphous inorganic material, and the average particle diameter and mixing ratio of the pore former.

About the exhaust system parts manufactured in Examples 1 to 5, Comparative Examples 1 to 4 and Reference Example 1, the characteristics of the surface coating layer (porosity, thermal conductivity, film thickness, initial film formability, continuous high temperature test results, The results of thermal shock resistance test results and comprehensive judgment results are shown in Table 2.
The porosity, thermal conductivity, film thickness, initial film formability, continuous high temperature test result, thermal shock resistance test result, and comprehensive judgment result of the surface coating layer were performed by the following methods.

(Measurement of thermal conductivity of surface coating layer)
The thermal conductivity (25 ° C.) of the surface coating layer of each exhaust system part of Examples 1 to 5, Comparative Examples 1 to 4 and Reference Example 1 was measured using a laser flash device (thermal constant measuring device: NETZSCH LFA457 Microflash). did.
In addition, when the heat conductivity (25 degreeC) of the base material (stainless steel base material) was measured similarly, the heat conductivity of the base material (stainless steel base material) was 25 W / mK.

(Measurement of porosity of surface coating layer)
The surface coating layer cut out to 3.1 mm size was measured with a three-dimensional measurement X-ray CT apparatus (TDM1000-IS / SP, manufactured by Yamato Scientific Co., Ltd.), and this was measured with three-dimensional volume rendering software (NVS (Nippon Visual). Since the pore volume can be measured by performing image processing with VG-Studio MAX) manufactured by Science Co., Ltd., the porosity can be calculated. 100 samples were taken from the surface coating layers of the exhaust system parts manufactured in Examples 1 to 5, Comparative Examples 1 to 4 and Reference Example 1 by the above measuring method, and the average value of the porosity was determined for the exhaust system parts. The porosity of the surface coating layer.

(Measurement of film thickness)
The film thickness was measured with a dual spop MP40 manufactured by Fischer Instruments.

(Evaluation of initial film formability)
Regarding the surface coating layer to be formed on the surface of the base material, using a scanning electron microscope (manufactured by Hitachi, FE-SEM S-4800), 10 SEM photographs focusing on the interface between the base material and the surface coating layer were taken, In those SEM photographs, voids are formed between the base material and the surface coating layer, and it was observed that peeling occurred, and “x” was assigned between the base material and the surface coating layer. The case where no voids were formed was indicated as “◯”.

(Continuous high temperature test)
About each exhaust system component of Examples 1-5, Comparative Examples 1-4, and Reference Example 1, the continuous high temperature test was done and the heat resistance of the surface coating layer was evaluated.
A test piece of 40 mm × 40 mm is prepared, and a surface coating layer is formed in half (40 mm × 20 mm). In that state, the surface coating layer was directed upward, and subsequently inclined by 90 ° from the horizontal direction, it was put into a firing furnace and held at 1000 ° C. for 15 minutes. Thereafter, the bottom of the base material of each exhaust system component, as well as dropping or alteration were confirmed. The sagging to the lower part was performed by confirming whether the boundary line between the formation part of the surface coating layer and the non-formation part was changed before and after the evaluation. The omission or alteration of the surface coating layer was confirmed visually.
In the column of “Continuous high-temperature test results” in Table 2, “×” indicates any change in film thickness (sagging to the bottom), dropout or alteration of the surface coating layer of the exhaust system part in the heat resistance test. The case where none of the change in the film thickness of the surface coating layer of the exhaust system part (sagging to the lower part), dropout, or alteration occurred was indicated as “◯”.

(Thermal shock resistance test results)
The following thermal shock resistance test was performed, and the thermal shock resistance of each exhaust system part of Examples 1 to 5, Comparative Examples 1 to 4, and Reference Example 1 was evaluated.
Each exhaust system part is heated to 900 ° C. in a firing furnace, and then the 900 ° C. exhaust system part is taken out of the furnace at room temperature. This was carried out for 50 cycles, with forced cooling by a fan as one cycle so that it would be / min. Thereafter, it was visually confirmed whether or not peeling occurred on the surface coating layer of each exhaust system component.
In the column of “Results of thermal shock resistance test” in Table 2, “×” indicates that the surface coating layer of the exhaust system component had peeled in the thermal shock resistance test, and there was peeling on the surface coating layer of the exhaust system component. What did not exist was shown as "○".

(Comprehensive judgment)
Based on the above initial film formability, continuous high-temperature test results, thermal shock resistance test results, and thermal conductivity measurement results, all passed ○, and at least one of the above characteristics is rejected. did. In addition, about thermal conductivity, the thing below 0.6 W / mK was evaluated as favorable, and the thing more than 0.6 W / mK was evaluated as bad.

In the exhaust system parts of Examples 1 to 5, the porosity of the surface coating layer is 30 to 70%, the thermal conductivity is as low as 0.10 to 0.40 W / mK, and the heat insulation is excellent. Was within a suitable range of 250 to 2000 μm, and the results of the initial film formability were good, the surface coating layer was not peeled off, and the adhesion to the substrate was excellent. In addition, the results of the continuous high-temperature test and the thermal shock resistance test were good, and it was found that the pores were not easily coalesced even at a high temperature, and the heat resistance, thermal shock resistance, and durability were excellent.
In particular, as shown in Example 5, even when a thick surface coating layer is formed on the substrate surface, the initial film formability is good and the thermal conductivity is 0.20 W / mK, which is extremely heat insulating. It was found that an excellent surface coating layer can be formed.

On the other hand, in the exhaust system part of Comparative Example 1, since no crystalline inorganic material is blended in the surface coating layer, it is considered that the heat resistance is inferior and the pores are likely to coalesce. The result is poor and rejected. In Comparative Example 2, the amount of the crystalline inorganic material is too large and the amount of the amorphous inorganic material is too small. There was a problem with the adhesion.
In Comparative Example 3, since the blending amount of the crystalline inorganic material is small, the heat resistance is lowered, and the continuous high-temperature test result is poor. In Comparative Example 4, alumina containing almost no silica was used as the crystalline inorganic material, and the reaction product particles were not generated. Therefore, the thermal conductivity was low, resulting in failure. In Reference Example 1, since the thickness of the surface coating layer was too thick, 3000 μm, the result of thermal shock resistance was poor.

Hereinafter, specific examples of the exhaust system parts of the present invention will be described with reference to the drawings.
The exhaust system component of the present invention is an exhaust pipe used as a member constituting an exhaust system connected to an internal combustion engine such as an automobile engine. The configuration of the exhaust system component described here is the same as that of the exhaust system component described above except that the base material is a cylindrical body.

Specifically, the exhaust system component of the present invention can be suitably used as, for example, an exhaust manifold.
Hereinafter, an exhaust system part of the present invention will be described by taking an exhaust manifold connected to an internal combustion engine such as an automobile engine as an example.

FIG. 4 is an exploded perspective view schematically showing an automobile engine according to the exhaust system component of the present invention and an exhaust manifold connected to the automobile engine.
FIG. 5A is a cross-sectional view of the automobile engine and the exhaust manifold shown in FIG. 4 taken along the line AA, and FIG. 5B is a line BB of the exhaust manifold shown in FIG. 5A. It is sectional drawing.

As shown in FIGS. 4 and 5A, an exhaust manifold 110 (exhaust system component shown in FIGS. 1 and 2) is connected to the automobile engine 100.
A cylinder head 102 is attached to the top of the cylinder block 101 of the automobile engine 100. An exhaust manifold 110 is attached to one side surface of the cylinder head 102.

The exhaust manifold 110 has a glove-like shape, and includes branch pipes 111a, 111b, 111c, and 111d corresponding to the number of cylinders, and a collective portion 112 that joins the branch pipes 111a, 111b, 111c, and 111d. Prepare.
A catalytic converter having a catalyst carrier is connected to the exhaust manifold 110. The exhaust manifold 110 has a function of collecting exhaust gas from each cylinder and further sending the exhaust gas to a catalytic converter or the like.
Then, the exhaust gas G discharged from the automobile engine 100 (in FIG. 5A, the exhaust gas is indicated by G and the direction in which the exhaust gas flows is indicated by an arrow) flows into the catalytic converter through the exhaust manifold 110. Then, it is purified by the catalyst supported on the catalyst carrier and discharged from the outlet.

As shown in FIG. 5B, the exhaust manifold 110 (exhaust system component of the present invention) includes a base material 120 made of metal and a surface coating layer 130 formed on the surface of the base material 120. .
In the exhaust manifold 110 (exhaust system component of the present invention) shown in FIG. 5B, the base material 120 is a cylindrical body, and the surface coating layer 130 is formed on the inner surface of the base material 120.

In the exhaust system component (exhaust manifold) of the present invention, the same configuration as the surface coating layer in the exhaust system component described above can be adopted as the configuration of the surface coating layer.
The exhaust manifold 110 shown in FIG. 5B shows an example in which the surface coating layer 130 has the same configuration as the surface coating layer 12 in the exhaust system component 10 shown in FIG. Although not shown in FIG. 13, crystalline inorganic material particles, reaction product particles, and pores are dispersed.

In the exhaust system component (exhaust manifold) of the present invention, the surface coating layer is preferably formed on the entire inner surface of the substrate. This is because the area of the surface coating layer that comes into contact with the exhaust gas is maximized and is particularly excellent in heat resistance. However, the surface coating layer may be formed only on a part of the inner surface of the substrate.
In the exhaust system component of the present invention, the surface coating layer may be formed on the outer surface in addition to the inner surface of the base material, or may be formed only on the outer surface of the base material.

Up to this point, an exhaust manifold has been described as an example of the exhaust system part of the present invention. However, the exhaust system part of the present invention is not limited to the exhaust manifold, and the exhaust pipe, the pipe constituting the catalytic converter, or the turbine It can also be suitably used as a housing or the like.
The number of branch pipes constituting the exhaust manifold is not particularly limited as long as it is the same as the number of cylinders of the engine. In addition, as a cylinder of an engine, a single cylinder, 2 cylinders, 4 cylinders, 6 cylinders, 8 cylinders etc. are mentioned, for example.

When manufacturing the exhaust system component of the present invention, the exhaust system component is the same as the exhaust system component of the present invention described with reference to FIG. Exhaust system parts can be manufactured.
In the exhaust system component of the present invention, when the surface coating layer is formed on the inner surface of the base material, it is desirable to use the base material composed of the first half member and the second half member as described above. .

Also in the exhaust system component of the present invention described here, the same effects as the effects (1) to (10) of the exhaust system component and the exhaust system component paint described with reference to FIG. 1 can be exhibited.

In the exhaust system component of the present invention, the surface coating layer is not necessarily formed on the entire surface of the substrate.
For example, when the exhaust system component of the present invention is used as an exhaust pipe, the surface coating layer may be formed on the inner surface of a cylindrical body as a base material. It is not necessary to form the entire surface of the inner surface of the cylindrical body as a material, and it is sufficient to form a surface coating layer at least in a portion where exhaust gas directly contacts.

The exhaust system component of the present invention is an exhaust system component comprising a single surface coating layer formed on the surface of the substrate, wherein the surface coating layer is made of an amorphous inorganic material containing silica. A layer, a crystalline inorganic material particle containing zirconia dispersed inside the amorphous inorganic material layer, a reaction product generated by a reaction between the crystalline inorganic material particle and the amorphous inorganic material layer The reaction product particles are crushed or acicular particles, and the ratio of the average pore diameter of the pores to the average particle diameter of the particles of the crystalline inorganic material (of the crystalline inorganic material). The average particle diameter of the particles / the average pore diameter of the pores) is 0.1 to 10, and the surface coating layer is an exhaust gas containing particles of the amorphous inorganic material, the pore former, and the crystalline inorganic material. It is an essential structure that is formed by applying and heating paint for system parts on the substrate. It is an element.
A desired effect can be obtained by appropriately combining the above-described essential components (for example, the configuration of the surface coating layer, the shape of the base material, the exhaust manifold, etc.) with the essential components.

10, 20, 30 Exhaust system component 110 Exhaust manifold 11, 21, 31, 120 Base material 12, 22, 32, 130 Surface coating layer 13 Amorphous inorganic material layer 14 Crystalline inorganic material particle 15 Reaction product particle 16 Pores

Claims (18)

A paint for exhaust system parts to be applied to a base material made of metal,
The exhaust system component paint includes amorphous inorganic material containing silica, crystalline inorganic material particles containing zirconia, and pore former particles,
The average particle size of the crystalline inorganic material particles is 0.1 to 150 μm,
The weight of the particles of the crystalline inorganic material with respect to 100 parts by weight of the amorphous inorganic material is 30 to 180 parts by weight,
The average particle size of the pore former particles is 0.1 to 25 μm,
A paint for exhaust system parts, wherein the weight of the pore former particles is 0.001 to 1 part by weight with respect to 100 parts by weight of the amorphous inorganic material. The exhaust system component paint according to claim 1, wherein carbon, carbonate, or a foaming agent is used as the pore former. The paint for exhaust system parts according to claim 1 or 2, wherein the pore former changes into a gas at 600 to 1000 ° C. The exhaust system component paint according to any one of claims 1 to 3, wherein the crystalline inorganic material particles contain 20% by weight or more of zirconia. The exhaust system component paint according to any one of claims 1 to 4, wherein the amorphous inorganic material contains 20 wt% or more of silica. A base material made of metal;
An exhaust system component comprising one surface coating layer formed on the surface of the substrate,
The surface coating layer includes an amorphous inorganic material layer containing silica, crystalline inorganic material particles containing zirconia dispersed in the amorphous inorganic material layer, crystalline inorganic material particles and Consists of reaction product particles and pores generated by reaction with the amorphous inorganic material layer,
The reaction product particles are crushed or acicular particles,
The ratio of the average pore diameter of the pores to the average particle diameter of the particles of the crystalline inorganic material (average particle diameter of the particles of the crystalline inorganic material / average pore diameter of the pores) is 0.1 to 10,
The surface coating layer is formed by applying and heating a coating for exhaust system parts including the amorphous inorganic material, pore-forming material particles and the crystalline inorganic material particles on a substrate. Features exhaust system parts. The exhaust system component according to claim 6, wherein 5 to 50% by weight of the crystalline inorganic material particles are in contact with the pores having a pore diameter of 0.1 to 50 μm. The exhaust system component according to claim 6 or 7, wherein the particles of the crystalline inorganic material contain 20% by weight or more of zirconia. The exhaust system component according to any one of claims 6 to 8, wherein the porosity of the surface covering material layer is 30 to 80%. The exhaust system component according to any one of claims 6 to 9, wherein an average pore diameter of the pores is 0.1 to 50 µm. The exhaust system component according to any one of claims 6 to 10, wherein an average particle diameter of the particles of the crystalline inorganic material is 0.1 to 150 µm. The exhaust system component according to any one of claims 6 to 11, wherein an average particle size of the reaction product particles is 0.01 to 25 µm. The exhaust system component according to any one of claims 6 to 12, wherein the surface coating layer has a thickness of 50 to 2000 µm. The exhaust system component according to any one of claims 6 to 13, wherein a thermal conductivity of the surface coating layer at room temperature is 0.05 to 2 W / mK. The particle of the crystalline inorganic material is a particle made of zirconia or a composite oxide containing zirconia and at least one of yttria, calcia, magnesia, ceria, alumina, and hafnia. Exhaust system parts described in Crab. The exhaust system component according to any one of claims 6 to 15, wherein the amorphous inorganic material is made of low-melting glass having a softening point of 300 to 1000 ° C. The exhaust system component according to claim 16, wherein the low-melting glass is a glass containing at least one of barium glass, boron glass, strontium glass, alumina silicate glass, soda zinc glass, and soda barium glass. The exhaust system component according to any one of claims 6 to 17, wherein the base material is an exhaust pipe, and a surface covering material layer is formed inside the exhaust pipe.